This invention covers the method and equipment in manufacturing Alternate Twisted Yarns whose twisting direction differs alternately in the yarn's longitudinal direction (the S twist area and Z twist area exist alternately).
Since irregular crimping can be produced by post-processing by such an Alternate Twisted Yarn, it is possible to manufacture the seersucker texture and wrinkled texture easily.
As a means for manufacturing this Alternate Twisted Yarn, this inventor has already suggested this method in the Official Gazette of Patent OPI Pub. 1996-246280. In this suggestion, a raw yarn is drawn out continuously or intermittently from the supply bobbin (which is fixed) and the raw yarn thus drawn out is inserted and passed to the twisting equipment rotating intermittently in one direction for intermittent twisting, which is then to be heat set after it is wound on to the take-up bobbin. The twisting equipment illustrated is such that the roller provided with a V-groove for rolling the yarn in the rotating cylindrical body's internal center is inserted at right angles to the shaft, and a nipper is provided to hold the yarn, utilizing centrifugal force. In any case, the yarn is to be twisted by means of the cylindrical body's rotation when passing through the said cylindrical body, and the twisting applied to the yarn is exactly opposite from the approach side to the delivery side on the twisting equipment.
In this case, the total number of twists generated on the twisting equipment's approach side and the delivery side is the same. However, since the yarn is wound on to the take up bobbin even during the twisting equipment's intermittent rotation stop period, the yarn twist on the twisting equipment's approach-side is sent to the delivery side through the twisting equipment, thereby untwisting the yarn on the delivery side, so that the twist is eliminated if this state were to continue. In reality, since the yarn on the delivery side cannot be untwisted because it is wound on to the take-up bobbin, the number of twists remaining on the delivery-side yarn becomes fewer than the total number of twists on the approach side. Extra twist sent to the delivery side from the approach side is wound on to the take-up bobbin as opposite twist in relation to the previous twist (i.e. S twist then next Z twist). Next, the twisting equipment restarts its intermittent rotation, newly twisting the yarns on the approach side and the delivery side in the reverse direction on the delivery side. The remaining yarn is untwisted just as it was in the earlier stages which is followed by new twisting, and then the rotation stops so that the aforementioned phenomenon occurs once again. Hence, the repeated rotation and stopping phenomenon described above continually repeats, thus producing the Alternate Twisted Yarn.
However, the above suggested equipment had a problem in that the cylindrical body which functions as a twisting device is rotated by a positive drive device in the yarn twisting direction. The rotation and stop must be repeatedly and alternately controlled, which in turn makes the twisting equipment's structure complicated, and the equipment cost, operating expenses, maintenance and control costs or the like are expensive.